The present invention relates to a belt supporting and tracking apparatus, and more particularly to an apparatus for controlling the lateral movement of a belt from its predetermined path while reducing wear of the inside surface of the belt as well as reducing torque required to drive the belt.
In an electrostatographic reproducing apparatus commonly in use today, a photoconductive insulating member is typically charged to uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the usual document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developing powder referred to in the art as toner. Most development systems employ a developer material which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charge pattern of the image areas in the photoconductive insulating area to form a powder image on the photoconductive area. This image may subsequently be transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure.
Many commercial applications of the above process employ the use of the photoconductive insulating member in the form of a belt which is supported about a predetermined path past the plurality of processing stations to ultimately form a reproduced image on copy paper. The location of the latent image recorded on the photoconductive belt must be precisely defined in order to have the various processing stations acting thereon optimize copy quality. To this end it is critical that the lateral alignment of the photoconductive belt be controlled within prescribed tolerances. Only in this manner will a photoconductive belt move through a predetermined path so that the processing stations disposed thereabout will be located precisely relative to the latent image recorded thereon.